Battery Assembly

ABSTRACT

A battery stack is provided having lower and upper battery tiers each formed of at least two battery cell arrays. A pair of brackets are provided for connecting the lower arrays along a top surface of the lower tier and connecting the upper arrays to a bottom surface of the upper tier. The lower and upper battery tiers are secured together by the brackets without hardware mounted to an exterior surface of the stack.

TECHNICAL FIELD

The present disclosure relates to a traction battery system for avehicle.

BACKGROUND

A traction battery for an electric vehicle, or hybrid-electric mayinclude many cells electrically connected. To attain a battery of asufficiently high voltage, cells are electrically connected serially.Groups of several cells can be coupled in arrays then stacked inparallel. And, although cell groups are physically arranged in aparallel fashion, they may be electrically coupled either in series orin parallel. Groups of individual cells within can be called a stack ora brick. A plurality of arrays are arranged in an stack and electricallyconnected to provide the desired voltage and current characteristics forthe particular application. Such connected plurality of battery cellarrays forms a battery. An example of a battery and array is disclosedin U.S. Pat. No. 8,323,818.

SUMMARY

According to one or more embodiments of the present disclosure a batterystack is provided. The battery stack includes lower and upper batterytiers each formed of at least two battery cell arrays. A pair ofbrackets is provided. One bracket connects the lower arrays along a topsurface of the lower tier. The other bracket connects the upper arraysto a bottom surface of the upper tier. The lower and upper battery tiersare secured together by the brackets without hardware mounted to anexterior surface of the stack.

In another embodiment, each of the brackets has a same mountingfootprint. The footprints are aligned to secure the lower and uppertiers together and allow airflow between the lower and upper batterytiers.

In another embodiment, one of the brackets is mounted to the lowerbattery tier to define a lower bracket having a top middle bracket and apair of side brackets. The top middle bracket connects the at least twolower battery arrays. The side brackets are spaced apart from the middlebracket and mounted to side regions on the lower battery tiers.

In another embodiment, the top middle bracket, the right side bracketand the left side bracket are spaced apart to define lower openings. Theupper bracket includes a plurality of apertures formed therethrough. Thelower openings and plurality of apertures allow airflow between thelower and upper battery tiers.

In another embodiment, the lower bracket is fastened to a top surface ofthe lower battery tier and the upper bracket is fastened to a bottomsurface of the upper battery tier. The mounting footprint of the lowerbracket and upper bracket is the same. Each mounting footprint includesa plurality of connection locations that align to connect the lower andupper battery tiers.

In another embodiment, the battery stack also includes a plurality ofarray frames each housing one of the battery arrays. Each of the arrayframes includes a pair of top rails and a pair of bottom rails. The topand bottom rails are connected by a pair of opposing end plates.

In another embodiment, the battery stack also includes a plurality offasteners. At least one fastener extends only through the connectionlocations on the upper bracket and the lower bracket to connect theupper battery tier to the lower battery tier and does not extend throughany of the array frames.

In another embodiment, the lower arrays are connected by the top middlebracket along adjacent top rails of the array frames and the upperarrays are connected by the tray along adjacent bottom rails of thearray frames.

In another embodiment, each of the lower array frames includes at leastone locating feature and each of the upper array frames includes atleast one locating member that cooperates with the locating feature of acorresponding lower array frame to align the upper and lower batterytiers.

In another embodiment, the lower battery arrays are connected by themiddle bracket along adjacent top rails of the array frames.

In another embodiment, wherein the upper battery arrays are connected bythe tray along adjacent bottom rails of the array frames.

In another embodiment, an access opening is defined in the upper batterytier such that a fastener is accessible through the access opening tofasten the upper and lower brackets.

According to one or more other embodiments of the present disclosure, abattery stack is provided. A lower battery tier has at least two lowerarrays of battery cells connected together. A top middle bracketconnects the two arrays and mounted to a top surface of the lower tier.A pair of side brackets is mounted along opposite side regions of thelower tier on the top surface of the lower tier. An upper battery tierhas at least two upper arrays of battery cells connected together. Abottom tray connects the two upper arrays and is mounted to a bottomsurface of the upper tier. The bottom tray is aligned and fastenedtogether with the top middle bracket and the pair of side brackets whenthe upper battery tier is mounted to the lower battery tier, therebysecuring and aligning the lower and upper tiers together. The bracketsand bottom tray allow airflow between the lower and upper battery arrayswhen the lower and upper battery tiers are secured together.

According to one or more other embodiments of the present disclosure,method of assembling battery arrays is provided. A pair of lower arraysof battery cells are positioned adjacent each other. A lower bracket isconnected to the pair of lower arrays to form a lower battery tier. Apair of upper arrays of battery cells is positioned adjacent each other.A bracket is connected to the pair of upper arrays to form an upperbattery tier. The upper battery tier is aligned with the lower batterytier. The upper bracket is aligned to the lower bracket through anaccess opening formed in the upper battery tier. A mounting footprint ofthe lower and upper brackets is the same and aligns to secure the upperbattery tier to the lower battery tier. The lower and upper bracketsallow an airflow between the lower and upper battery arrays.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an exploded view of a portion of a battery stackaccording to one embodiment of the present disclosure;

FIG. 2 illustrates a top view of a portion of the battery stack of FIG.1;

FIG. 3 illustrates a method of assembling the battery stack of FIG. 1;

FIG. 4 illustrates a method of assembling the battery stack of FIG. 1;

FIG. 5 illustrates a method of assembling the battery stack of FIG. 1;and

FIG. 6 illustrates a portion of the upper tier of the battery stack ofFIG. 1.

DETAILED DESCRIPTION

As required, detailed embodiments of the present invention are disclosedherein; however, it is to be understood that the disclosed embodimentsare merely exemplary of the invention that may be embodied in variousand alternative forms. The figures are not necessarily to scale; somefeatures may be exaggerated or minimized to show details of particularcomponents. Therefore, specific structural and functional detailsdisclosed herein are not to be interpreted as limiting, but merely as arepresentative basis for teaching one skilled in the art to variouslyemploy the present invention.

A battery for a hybrid electric vehicle may include many cellselectrically connected serially in order to provide a sufficiently highvoltage. Groups of several cells can be coupled longitudinally in arraysand then stacked with groups arranged in parallel compartments. Aconnected plurality of cell arrays forms a battery stack.

Vehicles which utilize a high-voltage (HV) battery may include an energysystem having a battery pack with components such as one or more batterymodules with battery cells, a body electrical control module (BECM), anda DC/DC converter module with a DC/DC converter unit. The battery cellsmay provide energy to operate a vehicle drive motor and other vehiclesystems. The battery pack may be positioned at several differentlocations including below a front seat, a rear seat, or a locationbehind the rear seat of the vehicle. Two battery cell arrays may be inelectrical communication with the BECM, DC/DC converter unit and othervehicle components.

The BECM may receive input signals from various control systems, processinformation included in the input signals and generate appropriatecontrol signals in response thereto. These control signals may activateand/or deactivate the various components. The DC/DC converter unit mayconvert high voltage from the battery cells into low voltage for use bythe components and systems.

Each battery array may include a plurality of battery cells. The batterycells, such as a prismatic cell, may include electrochemical cells thatconvert stored chemical energy to electrical energy. Prismatic cells mayinclude a housing, a positive electrode (cathode) and a negativeelectrode (anode). An electrolyte may allow ions to move between theanode and cathode during discharge, and then return during recharge.Terminals may allow current to flow out of the cell for use by thevehicle.

Different battery pack configurations may be available to addressindividual vehicle variables including packaging constraints and powerrequirements described further herein. The battery cells may be heatedand/or cooled with a thermal management system. Examples of thermalmanagement systems may include air cooling systems, liquid coolingsystems and a combination of air and liquid systems.

Air cooling systems may use one or more blowers and ducts to distributeair across, for example, the components of the battery module and DC/DCconverter module to remove heat generated during vehicle operations.These operations may include charging and discharging the battery cellsas well as removing the heat generated during voltage conversion in theDC/DC converter unit. Vehicle components in the environment surroundingthe battery pack may be utilized to assist in managing the batterypack's thermal conditions.

Referring to FIG. 1, a battery stack 10 is illustrated. The batterystack 10 includes a lower battery tier 12 having at least two lowerarrays 16 of battery cells connected together. The battery stack 10 alsoincludes an upper battery tier 14 having at least two upper arrays 18 ofbattery cells connected together. The arrays of battery cells 16, 18 areshown and discussed further in FIGS. 3-5.

In order to secure the upper tier 14 to the lower tier 12, a lower tierattachment 20 and an upper tier attachment 30 are provided.

The attachment scheme includes the lower tier attachment 20 having a topmiddle bracket 22 connecting the two arrays and mounted to a top surface24 of the lower tier 12. The lower tier attachment 20 also includes sidebrackets 26 mounted on the top surface 24 at opposite sides 28 of thelower tier 12. As shown, the lower tier attachment 20 includes one topmiddle bracket 22 at least two side brackets 26. However, if the lowerbattery tier 12 included a different number of lower battery arrays 16,additional middle brackets 22 may be provided.

The upper tier attachment 30 includes a bottom tray 32 connecting thetwo upper arrays 18 and mounted to a bottom surface 34 of the upper tier14.

The lower tier attachment 20 and upper tier attachment 30 are alignedand fastened together when the upper battery tier 14 is mounted to thelower battery tier 12. The upper tier attachment 30 and lower tierattachment 20 align the lower tier 12 to the upper tier 14 and ensurethe lower tier 12 and upper tier 14 remain secured to each other duringshipping and high impacts or any other situation where the battery stack10 may experience high vibration or forces.

Each of the lower tier attachment 20 and upper tier attachment 30 hasmounting footprint 40 being the same for being attached to the lowertier 12 and upper tier 14 respectively. The mounting footprint 40 isdefined by a plurality of fastening locations 44 such as apertures orlugs or any other suitable fastening location. This commonality betweenthe mounting footprint 40 of the upper tier attachment 30 and lower tierattachment 20 reduces complexity in manufacturing and improves qualityby eliminating the possibility of assembly errors. Reducing complexityalso reduces manufacturing costs.

The fastening locations 44 are adapted to mate with fastening features46 defining a mounting pattern 48 disposed on an array frame 50. Each ofthe upper and lower battery arrays is disposed in an array frame 50.Each of the array frames 50 includes a pair of top rails 52 and a pairof bottom rails 54. The top rails 52 and bottom rails 54 are connectedby a pair of opposing end plates 56 to form the array frame 50 for eachbattery array. The top rails 52 are common in all of the array frames50, whether the array frame 50 is for an array on the lower tier 12 orupper tier 14. Likewise, the bottom rails 54 are common in all of thearray frames 50.

The common top rails 52 and common bottom rails 54 define the commonmounting pattern 48. By having the top and bottom mounting pattern 48the same for each of the lower tier 12 and upper tier 14, it allowscommonality between the brackets for each of the lower tier 12 and uppertier 14. For example, the middle bracket 22 can be the same for each ofthe lower tier 12 and upper tier 14, or additional tiers if necessary.Likewise, the bottom tray 32 may be secured the bottom surface 34 ofeach of the lower tier 12 and upper tier 14. In the lower tier, thebottom tray 32 may be used to secure the stack 10 in the vehicle, forexample. This commonality of the top rails 52 and bottom rails 54reduces complexity in manufacturing, improves quality by eliminatingassembly errors, and manufacturing costs.

FIGS. 3-5 illustrate a method of simplified assembly of the batterystack 10. As shown in FIG. 3, the array of battery cells 16 extends in alongitudinal direction 62. The pair of lower battery cell arrays 16 arepositioned adjacent each other in a lateral direction 64. The lowerarrays 16 are connected by the top middle bracket 22 along adjacent toprails 52 by a plurality of fasteners 60. The lower right side bracket 26and left side bracket 28 are also connected to the top rails 52 on thelateral side regions 66 of each of the lower arrays 16. As illustrated,the fasteners 60 are bolts. However, any type of suitable fastener iscontemplated, including screws, rivets, or welds, for example.

Likewise, the upper arrays of battery cells 18 extend in thelongitudinal direction and are positioned adjacent each other in thelateral direction 64. The upper arrays 18 are connected by the bottomtray 32 along adjacent bottom rails 54 of the array frames by aplurality of fasteners 60.

After the defining the lower tier 12 and the upper tier 14 by connectingthe lower arrays 16 and the upper arrays 18 respectively, the upperbattery tier 14 is aligned with the lower battery tier 12, as shown inFIG. 4. Second stage fasteners 70 extend through the bottom rail 54 andthe bottom tray 32 of the upper tier 14 and through the top middlebracket 22 to fasten the upper tier 14 to the lower tier 12.

An access opening 74 formed in the upper tier 14 allows the upper tier14 to be fastened to the lower tier 12 without heavy and cumbersomeclamps or brackets that extend around the stack. The access opening 74extends in a vertical direction between adjacent battery arrays 18. Asillustrated, the fasteners 70 are torque screws. However, any type ofsuitable fastener is contemplated, including bolts, rivets, or welds,for example.

Each of the lower array frames 50 includes at least one locating feature80. Each of the upper array frames 50 includes at least one locatingmember 82 that mates with the locating feature 80 of a correspondinglower array frame 50. Mating the locating feature 80 to the locatingmember aids in aligning the upper tier 14 to the lower tier 12.

As shown in FIG. 5, the upper tier 14 is secured to the lower tier 12along the lateral side regions 66 with a third stage of fasteners 90.The fasteners 90 extend through the bottom rail 54 and the bottom tray32 of the upper tier 14 and through the side brackets 26, as shown onthe left, to fasten the upper tier 14 to the lower tier 12. Likewise,additional fasteners 90 extend through the bottom rail 54 and the bottomtray 32 of the upper tier 14 and through the side bracket 26 on theright to fasten the upper tier 14 to the lower tier 12. As illustrated,the fasteners 90 are bolts. However, any type of suitable fastener iscontemplated, including screws, rivets, or welds, for example.

FIG. 6 illustrates a section view along section 6-6 in FIG. 1essentially showing the top view of the bottom tray 32. The bottom tray32 includes a plurality of openings 94 so that bottom tray 32 does notrestrict airflow between the lower array 16 and the upper battery array18. For example, airflow that provides thermal management includingcooling and heating, may flow from a duct connect to the airconditioning system into a battery chamber. The incoming airflow may bedirected by a pusher-type fan. Airflow exiting the battery chamber mayflow into an exhaust duct which may be directed outside the vehicle. Theexhaust duct may include a puller-type fan to increase exhaust airflow.

FIG. 6 further illustrates the mounting footprint 40 being the same forattaching the lower tier 12 to upper tier 14. The mounting footprint 40includes a plurality of connection locations for connecting the bottomtray 32 to the middle bracket 22, and side brackets 26. The mountingfootprint 40 includes lateral connection locations 96 through whichfasteners 90 extend to connect the tray 32 to the side brackets 26 to.The mounting footprint 40 also includes central connection location 98through which fasteners 70 extend to connect the middle bracket 22 tothe bottom tray 32. The connection locations may be apertures or lugs orany other suitable fastening location. As discussed previously, thecentral connection locations are accessible only through the accessopenings 74 in the upper tier 14.

As shown in FIGS. 3-5, the middle bracket 22, has corresponding centralconnection locations 98. Further, the side brackets 26 havecorresponding lateral connection locations 96. This commonality betweenthe upper tier attachment 30 and lower tier attachment 20 reducescomplexity in manufacturing and improves quality by eliminating thepossibility of assembly errors. Reducing complexity also reducesmanufacturing costs.

While exemplary embodiments are described above, it is not intended thatthese embodiments describe all possible forms of the invention. Rather,the words used in the specification are words of description rather thanlimitation, and it is understood that various changes may be madewithout departing from the spirit and scope of the invention.Additionally, the features of various implementing embodiments may becombined to form further embodiments of the invention.

What is claimed is:
 1. A battery stack comprising: lower and upperbattery tiers each formed of at least two battery cell arrays; and apair of brackets, one bracket connecting the lower arrays along a topsurface of the lower tier, the other bracket connecting the upper arraysto a bottom surface of the upper tier, and the lower and upper batterytiers secured together by the brackets without hardware mounted to anexterior surface of the stack.
 2. The battery stack of claim 1 whereineach of the brackets has a same mounting footprint and wherein thefootprints are aligned to secure the lower and upper tiers together, andallow airflow between the lower and upper battery tiers.
 3. The batterystack of claim 1 wherein one of the brackets is mounted to the lowerbattery tier to define a lower bracket having a top middle bracket and apair of side brackets, wherein the top middle bracket connects the atleast two lower battery arrays, and wherein the side brackets are spacedapart from the middle bracket and mounted to side regions on the lowerbattery tiers.
 4. The battery stack of claim 3 wherein the top middlebracket, the right side bracket and the left side bracket are spacedapart to define lower openings, wherein the upper bracket includes aplurality of apertures formed therethrough, and wherein the loweropenings and plurality of apertures allow airflow between the lower andupper battery tiers.
 5. The battery stack of claim 3 wherein the lowerbracket is fastened to a top surface of the lower battery tier and theupper bracket is fastened to a bottom surface of the upper battery tier,wherein the mounting footprint of the lower bracket and upper bracket isthe same, and wherein each mounting footprint includes a plurality ofconnection locations that align to connect the lower and upper batterytiers.
 6. The battery stack of claim 3 further comprising a plurality ofarray frames each housing one of the battery arrays, wherein each of thearray frames includes a pair of top rails and a pair of bottom rails andwherein the top and bottom rails are connected by a pair of opposing endplates.
 7. The battery stack of claim 6 further comprising a pluralityof fasteners, wherein at least one fastener extends only through theconnection locations on the upper bracket and the lower bracket toconnect the upper battery tier to the lower battery tier such that theat least one fastener does not extend through any of the array frames.8. The battery stack of claim 6 wherein the lower arrays are connectedby the top middle bracket along adjacent top rails of the array framesand wherein the upper arrays are connected by the tray along adjacentbottom rails of the array frames.
 9. The battery stack of claim 6wherein each of the lower array frames includes at least one locatingfeature and each of the upper array frames includes at least onelocating member that cooperates with the locating feature of acorresponding lower array frame to align the upper and lower batterytiers.
 10. The battery stack of claim 6 wherein the lower battery arraysare connected by the middle bracket along adjacent top rails of thearray frames.
 11. The battery stack of claim 1 wherein the upper batteryarrays are connected by the tray along adjacent bottom rails of thearray frames.
 12. The battery stack of claim 1 wherein an access openingis defined in the upper battery tier such that a fastener is accessiblethrough the access opening to fasten the upper and lower brackets.
 13. Abattery stack comprising: a lower battery tier having at least two lowerarrays of battery cells connected together; a top middle bracketconnecting the two arrays and mounted to a top surface of the lowertier; a pair of side brackets mounted along opposite side regions of thelower tier on the top surface of the lower tier; an upper battery tierhaving at least two upper arrays of battery cells connected together;and a bottom tray connecting the two upper arrays and mounted to abottom surface of the upper tier, wherein the bottom tray is aligned andfastened together with the top middle bracket and the pair of sidebrackets when the upper battery tier is mounted to the lower batterytier, thereby securing and aligning the lower and upper tiers together,and wherein the brackets and bottom tray allow an airflow between thelower and upper battery arrays when the lower and upper battery tiersare secured together.
 14. The battery stack of claim 13 furthercomprising a plurality of fasteners, wherein an upper mounting footprintis defined by the bottom tray and a lower mounting footprint is definedby the top middle bracket and the side brackets, wherein the uppermounting footprint and lower mounting footprint are the same, whereineach mounting footprint includes a plurality of connecting locationsthat align to connect the lower and upper battery tiers, and wherein atleast one of the fasteners extends through a connecting location definedin the top middle bracket and the bottom tray to secure the lower andupper battery tiers together.
 15. The battery stack of claim 14 whereinan access opening is defined in the upper battery tier such that theconnection location is accessible through the access opening to fastenthe bottom tray and the top middle bracket together.
 16. The batterystack of claim 14 further comprising a plurality of array frames eachhousing one of the arrays, wherein each of the array frames includes apair of top rails and a pair of bottom rails, wherein the top and bottomrails are connected by a pair of opposing end plates, wherein the lowerarrays are connected by the top middle bracket along adjacent top railsof the array frames and the upper arrays are connected by the bottomtray along adjacent bottom rails of the array frames, and wherein theplurality of fasteners extend only through the connection locations onthe upper bracket and the lower bracket to connect the upper batterytier to the lower battery tier such that the fasteners do not extendthrough any of the array frames.
 17. A method of assembling batteryarrays comprising: positioning a pair of lower arrays of battery cellsadjacent each other; connecting a lower bracket to the pair of lowerarrays to form a lower battery tier; positioning a pair of upper arraysof battery cells adjacent each other; connecting a bracket to the pairof upper arrays to form an upper battery tier; aligning the upperbattery tier with the lower battery tier; and fastening the upperbracket to the lower bracket through an access opening formed in theupper battery tier, wherein a mounting footprint of the lower and upperbrackets is the same and aligns to secure the upper battery tier to thelower battery tier and wherein the lower and upper brackets allow anairflow between the lower and upper battery arrays.
 18. The method ofclaim 17, wherein the upper bracket is defined by a bottom tray and thelower bracket is defined by a top middle bracket and a pair lower sidebrackets and wherein the upper and lower arrays each include an upperand lower array frame containing each of the upper and lower batteryarrays respectively, further comprising fastening at least one fastenerthrough the bottom tray and the top middle bracket such that the atleast one fastener does not extend through the upper array frame or thelower array frame.
 19. The method of claim 18, wherein each of the arrayframes includes a pair of top rails and a pair of bottom rails andwherein the top and bottom rails are connected by a pair of opposing endplates, further comprising fastening the lower arrays together by thetop middle bracket along adjacent top rails of the lower array framesand fastening the upper arrays together by the bottom tray alongadjacent bottom rails of the upper array frames.
 20. The method of claim18 further comprising connecting the bottom tray to the top middlebracket at a connection location accessible through the access opening.